In various industrial machines and the like, eccentric speed reducers are used as speed reducers capable of achieving a high speed reduction ratio. Such eccentric speed reducers include crankshafts, external gears that are eccentrically rotated by rotation of the crankshafts, a casing provided with internal teeth for meshing with external teeth of the external gears, and a carrier that rotatably supports the crankshafts, and an eccentric speed reducer as described in Patent Document 1 is known. In the eccentric speed reducer described in Patent Document 1, a carrier that rotatably supports a plurality of crankshafts is made up of a base carrier (base portion) that rotatably supports one end of each of the crankshafts and an end carrier (end plate portion) that rotatably supports the other end. The base carrier is integrally formed with a plurality of struts (column portions) extending from the base carrier toward the end carrier and connecting the base carrier and the end carrier.
Patent Document 1: JP2003-83400A (page 3, FIG. 1, FIG. 2)